This dissertation utilizes content identifying methodologies based on preference and expected price ratings, and a free response format survey, to examine environmental factors that influence human perception of commercial landscapes and storefronts. Survey respondents rated scenes of commercial landscapes and storefronts according to their preference for the scene and their expected price of goods sold in the establishments depicted. Signs were removed from the scenes to permit evaluation of design characteristics in a context that is free from the external influence of information conveyed through product and retailer image. The respondents provided additional information about their shopping habits, shopping preferences, demographic background, and the scenes being rated. Preference and expected price ratings were analyzed using nonmetric factor analysis, to obtain dimensions or groupings of scenes which are the result of common stimuli or visual characteristics. The content or common stimuli of each dimension was then identified using information provided by the respondent. The relationship between the dimensions and respondent characteristics was then examined. A positive linear relationship was identified between preference and expected price ratings. This finding indicates that in the absence of signs, people tend to fall back on their preferences to make judgments about the price of merchandise sold in commercial landscapes. While there were commercial landscapes that were judged to offer low prices, those landscapes were also associated with the negative characteristics of poor service, poor quality and dangerous environments. The findings of this dissertation research provide evidence that reaffirms the importance of coherence, complexity, mystery and legibility in environmental perception, and supports prospect refuge theory. Respondents preferred commercial landscapes with interesting and involving environments. Storefronts that utilize angles, arcades, porticos, towers, and other forms of facade articulation were preferred. Likewise, visually rich and well . textured materials, such as brick, interlocking pavers and stamped concrete increased preference for commercial landscapes. Storefronts that utilize accent features, such as towers or awnings were found to have greater legibility, because these features assist in way finding. / Ph. D.

This dissertation is concerned with airport ground network operations and runway design problems. An aircraft landing simulation model is proposed to predict landing aircraft operations in airfield networks considering gate location and taxiway network information. By using the integrated simulation results, an improved dynamic programming model is established to solve the runway exit location problem. The simulation model uses aircraft kinematic functions coupled with individual parameters to describe the landing process. A multiobjective optimization and a shortest path algorithm are used to predict the aircraft exit choice and expected taxiway path in a runway-taxiway network. By recognizing pilot motivation during the landing process, several influencing factors such as terminal location, traffic density, runway and weather conditions are considered in the aircraft landing simulation. Random variables such as aircraft approach speed, deceleration rate and runway exit speed are created to represent the stochastic aircraft landing behavior by using a Monte Carlo sampling technique. The model results, with some simplifications, could be used to solve runway exit location problem by providing the expected distribution of aircraft landing distances and aircraft runway occupancy times. With real-time input data, the model could also provide information on aircraft exit choice, runway occupancy times and shortest taxiway path to an assigned terminal location for both the pilot and the air traffic controller in a ground traffic automatic control system. The dynamic programming model is based on previous research results with substantial improvements. Instead of only focusing on the runway configuration, the proposed model recognizes airline terminal location as an influence factor in the runway exit location problem and introduces this influence in the optimization procedure. An interactive computer program has been developed in C language on a RISC 6000 workstation to perform all these tasks. The choice of a workstation platform improves the performance of the dynamic programming algorithm when compared to personal computer solutions. / Ph. D.

Ph. D.

Ph. D.

M.A.

M.S.

M.S.

M.S.

Although Automated Guided Vehicle Systems (AGVS) have been around for more than thirty years, designing an AGVS is still a difficult process because of the interaction of numerous system decisions. The many important elements and variables that must be considered when designing AGVS include the number and location of pickup and delivery stations, the number of vehicles, the routes used by vehicles, the dispatching rules, and the guide path layout. There are two basic categories of AGVS control: static and dynamic. A static control system requires the automated guided vehicle (AGV) to run the same route continuously with stops at each pickup/delivery station. On the other hand, vehicles in the dynamic control system can be routed to different stations using different paths. There are two types of dynamic vehicle control: workcenter-initiated and vehicle-initiated dispatching rules. The system invokes the workcenter-initiated dispatching rule when one workcenter has a pending request and more than one vehicle is available to pickup the request. Vehicle-initiated dispatching rule is employed when one vehicle is free and there is more than one outstanding request in the system. Most research to date analyzes only the static aspect of AGVS. This research attempts to find the minimum number of vehicles needed in an AGVS, using dynamic control of the vehicles, such that the chance of a vehicle-initiated situation occurring is less than a given very small threshold. Under these conditions, load requests will have the least chance of waiting to be picked up. Due to the stochastic behavior of the AGV systems, the proportion of time that the system is in either workcenter- or vehicle-initiated rules is unknown. In order to minimize the waiting time for the load requests while at the same time maintaining a minimum number of vehicles in the system, this research utilizes only workcenter-initiated dispatching rules. A model using queueing theory and Markovian processes is developed to investigate the relationships among empty vehicle travel time, number of vehicles, and the various types of workcenter-initiated dispatching rules. This model is then used to formulate a dispatching-rule based algorithm (DRBA) to determine the minimum number of vehicles. Also, given the number of vehicles required in the system, this research investigates the impact of the nearest-vehicle and farthest-vehicle dispatching rules on the steady-state system performance, e.g., the average waiting time of the load request. The model and algorithm are able to (1) improve the estimate of the number of vehicles required in an AGVS in the early design phase; (2) provide a better understanding of the efficiency of using the different types of workcenter-initiated dispatching rules for various workload conditions; and (3) generate analytical results that can be used as initial estimates for more detailed simulation studies. / Ph. D.

A two-dimensional analysis is applied to the vibrations of inflatable dams under overflow conditions. The static analysis yields the equilibrium state for both the free surface profile and the shape of the dam. The dynamic analysis investigates the small vibrations of the inflatable dam about the equilibrium state. The dam is inextensible, air-inflated, and has two anchored points. The base width, curved perimeter, and internal air pressure are given. The overflow is incompressible, inviscid, and irrotational, and the total head is specified. In the static analysis, the self-weight of the dam is neglected, and the equations of equilibrium from membrane theory are solved by a multiple shooting method. The boundary element method is used to solve Laplace’s equation defined on the overflow domain. An iterative scheme is adopted to obtain the shape of the dam, as well as the location of the free surface. From the equilibrium state, the dynamic analysis is established by a finite difference form of the membrane’s equations of motion and the velocity potential problem is formulated by the boundary element method. After the eigenvalue problem is solved, the eigenvalues and eigenvectors obtained are employed to describe the vibrations of the dam. The effects of the dam‘s density and damping coefficient are illustrated. / Ph. D.